The present invention relates to a plasma processing method using a plasma processing apparatus and, in particular, to a plasma processing method which suppresses particles.
For manufacturing highly minitualized, complicated semiconductor devices, techniques for plasma-etching of a film, which is a material to be etched, with high selectivity and perpendicularity are needed. As one of them, it has become an important problem to plasma-etch a silicon nitride (Si3N4) film perpendicularly with high selectivity with respect to a silicon oxide (SiO2) film used as material of an underlying layer or a mask.
As a technique for solving this problem, a method for etching a silicon nitride film with high selectivity with respect to a silicon oxide film by using gas composed of C, H, and F and having a ratio of F to H of 2 or less such as CH3F and CH2F2 is disclosed in JP-A-60-115232. Furthermore, a technique for enhancing the selectivity by increasing and decreasing a wafer bias power value during silicon nitride etching is disclosed in JP-A-6-267895.